Bio-Based Eucommia Rubber Foams With Shape Memory Behavior: Microstructural Engineering and Functional Applications

Thermoresponsive shape memory polymers have garnered significant attention in sustainable packaging solutions due to their energy-efficient actuation and adaptive functionalities. In this study, we report a novel cellular material derived from natural Eucommia rubber (NER) with excellent shape memory and thermoshrinkable properties. The article described the preparation and properties of these foamed NER composites and investigated the impact of the foaming agent's content on the mechanical, thermal, and shape memory properties of these composites. Particularly noteworthy is the discovery of shape memory behavior in the cells, a phenomenon not reported in other literature. The experimental results indicated that as the amount of foaming agent AC increased, the cell size of the composite material rose from 40 to 70 μm. The density decreased significantly from 0.42 to 0.21 g/cm 3 , and the tensile strength of the composite material also decreased from 9.9 to 3.5 MPa. Besides these fundamental performance changes, the NER composites demonstrated outstanding shape memory properties. The excellent shape memory properties were closely linked to the cross-linking structure and crystal structure within the composite material. Remarkably, this manuscript is the first to report the preparation of thermal shrinkage foaming rubbers and observe their thermal shrinking behavior. The foamed material developed in this study is expected to demonstrate broad application prospects in multiple fields, including heat-shrinkable packaging, thermal insulation and protection, and solid–liquid separation.